Like many of Mach III’s custom designs, this brake design began with an inquiry about a catalog model spring engaged brake. An engineer working on a drive system needed a holding brake to prevent a Rexroth RAK-8D actuator from being back driven and losing position if air pressure was lost. The connection to the actuator was a 19mm square rather than a typical round shaft and key and, since the system would be on an offshore oil drilling platform, the brake had to be enclosed.

While it was possible to enclose the D4F3R-STH brake the engineer had inquired about and produce it with a square input, he would have to make changes to his design to connect the brake to the motor. Instead, Mach III engineers presented the concept of this enclosed spring engaged, air released brake with a flange containing six through holes on an 80mm bolt circle to connect directly to the actuator. The brake has 500 pound inches of torque and requires 77 PSI to release. The time span between the initial inquiry and the quotation for the custom design was just 4 days. The lead time to produce this completely custom brake solution was only 3 short weeks.